Water-based Modification of Cellulose Nano Fibrils for Packaging Applications. Kendra Fein Doug Bousfield William Gramlich

Transcription

1 Water-based Modification of Cellulose Nano Fibrils for Packaging Applications Kendra Fein Doug Bousfield William Gramlich 1

2 Motivation Environmental Plastic Microplastics in oceans centuries to degrade transports plasticizers and flame retardants absorbs contaminants from environment Ingested by wildlife smells like food to fish impacts commercial fishing 2

3 Motivation Shift in Market Change in demand for biodegradable packaging material NYC banned polystyrene food containers in 2015 bagasse (sugarcane) paper Costa Rica proposed to ban all single-use plastic by 2021 poly(lactic acid) (PLA) PLA-coatedpaper 3

4 Research Introduction Create competitive bio-based packaging material limited or expensive options available can be difficult to match properties of plastic Modified CNF can offer some film benefits Cellulose nanofibril film 4

5 What is CNF Highly fibrillated cellulose Process Development Center 1000 kg/day capacity Upscaling potential and simplicity of material process 2 4 mm (Smook 2002) µm (Smook 2002) cellulose fibers from wood 5

6 What is CNF Highly fibrillated cellulose Process Development Center 1000 kg/day capacity Upscaling potential and simplicity of material process s mm (Moon et al. 2011) µm (Moon et al. 2011) MFC 5

7 What is CNF Highly fibrillated cellulose Process Development Center 1000 kg/day capacity Upscaling potential and simplicity of material process µm (Moon et al. 2011) nm (Moon et al. 2011) CNF 5

8 Poor oxygen barrier PAPER Hydrophilic Hygroexpansive Cellulose derived from trees Moisturesensitive Biobased Brittle PLA Typically hydrophobic Heat resistant to only 40 C CNF Good grease and oxygen barrier vs paper 6

9 Research Objectives Understand relationship between modification and properties Chemically modify CNF to adjust film properties strength hydrophobicity oleophilicity flexibility dispersion Consider up-scaling 7

10 Step 1: Investigate Unmodified CNF Films Develop repeatable process in lab modify CNF in water with various chemistries generate free standing films test mechanical and barrier properties Films properties affected by: temperature humidity processing drying rates 8

11 Film Properties to Investigate Mechanical/Structure Instron Tensile stress, strain Scanning Electron Microscope formation, visual analysis Porosity Opacity Barrier Water Contact Angle hydrophilicity Kit Test oleophilicity Water vapor transmission 9

12 Step 2: Water-based Modification Surface modification in water process developed in Gramlich group Previous methods require several solvent exchange steps Up-scaling potential 10

13 CNF Purification Steps Dialysis Separation by concentration CNF in dialysis bags Not up-scalable Centrifugation Separation by density Series of water replacement Up-scalable 12

14 Step 3: Thiol-ene Reaction very versatile + radical initiation highly-reactive double-bond molecule thiol thiolfunctionalized molecule 13

15 Step 4: Modified CNF Film Analysis Strength vs. flexibility/stretch Barrier properties Optical properties Dimensional stability CNF swells and shrinks testing in TAPPI conditions Biodegradability Recyclability 14

16 Cellulose Polymer Norbornene- Functionalized Thiol- Functionalized 11

17 Cellulose Polymer Norbornene- Functionalized Thiol- Functionalized 11

18 Future Work Evaluate film surface and thickness Improve basis weight measurements Monitor physical, optical, and barrier properties Secondary modification for toughness and/or hydrophobicity Continue PhD proposal 16

19 Thank you Project Sponsored by: Paper Surface Science Program (PSSP) P3Nano Collaboration 17

20 Opacity (%) Opacity Increasing Weight CNF CNF CNF CNF NaOH CNF CNF CNF CNF x ccnf x ccnf 10x ccnf 10x 10x 10x Basis Weight (g/m 2 ) 10x 10x 10x 20

21 CNF Films Thicknesses Sample Name n Thickness (μm) Approximate Drying Time petri dish days forced air-dried hours heated 70 C mins heated 80 C mins heated 90 C mins air-dried samples constrained with a ring shrinking in heated samples less petri dish shrinking at lower basis weights 21

22 Young's (Elastic) Modulus E = 2,734 MPa Tensile Strain at Break Tensile Stress at Break Area under curve = Tensile Energy Absorption (TEA) = Tensile Toughness 22

23 Stress (MPa) g/m 2 Stress-Strain Curves All Drying Types petri dish forced air 70 C 80 C 90 C Strain (mm/mm) 23

24 Young s (Elastic) Modulus of Common Materials LDPE PET HDPE unmodified CNFfilms polystyrene (foam) rubber (small strain) PTFE (teflon) polypropylene diatom frustules (silicic acid) polystyrene (solid) nylon medium-density fiberboard Young s Modulus (GPa) 24

25 Stress at Failure (MPa) Tensile Stress NaOH CNF 2.5x CNF CNF 5x CNF 10x CNF Basis Weight (g/m 2 ) 25

26 Toughness (kj/m 3 ) 16 Tensile Toughness x CNF NaOH CNF x CNF 10x CNF Basis Weight (g/m 2 ) 26

27 Strain at Failure 0.20 Tensile Strain x CNF NaOH CNF CNF 5x CNF 10x CNF Basis Weight (g/m 2 ) 27

28 Young's Modulus (GPa) 2.50 Young s Modulus CNF NaOH CNF 2.5x ccnf 5x ccnf 10x ccnf Films 28